This invention relates to a punch press for forming holes in a workpiece. The invention more particularly relates to apparatus in which a melting tool such as a plasma-arc torch acts in conjunction with the punch press. The combination of a punch press and a plasma-arc torch is disclosed in Brolund et al U.S. application Ser. No. 735,087, filed Oct. 22, 1976, now U.S. Pat. No. 4,063,059 entitled Punch Press With Cutting Torch and assigned to the assignee of the present invention.
As disclosed in the Brolund et al application, the punch press includes a reciprocating punch which coacts with an underlying die to form comparatively small and substantially regularly shaped holes in the workpiece. The plasma-arc torch is spaced transversely from the punch and is used to cut sections from the workpiece and to form large and irregularly shaped holes in the workpiece. The torch operates by ionizing a column of gas with an electric arc to produce temperatures up to 30,000.degree. F. As the high velocity, high temperature plasma stream strikes the workpiece, the heat instantly melts the metal while the stream blows the molten metal downwardly away from the workpiece. A duct is disposed just beneath the workpiece in alinement with the torch and serves to collect the molten metal.
The workpiece is supported on a table which is adapted to be moved in a fore-and-aft direction on a frame or a bed in order to shift the workpiece to various fore-and-aft positions relative to the punch and the torch. Carried on the rear of the table are one or more clamps having upper and lower jaws for gripping the rear edge of the workpiece. The clamps may be shifted transversely on the table to move the workpiece to various transverse positions beneath the punch and the torch.
To enable the workpiece table to move forwardly past the die and the duct, the table is formed by two conjointly movable sections which are spaced apart so as to define a fore-and-aft extending throat in the table. As a result of the throat, the table may be moved forwardly to positions in which the two table sections straddle the die and the duct. Being required to accommodate both the die and the transversely spaced duct, the throat is relatively wide and thus a gap of considerable width is left between the two table sections so that the portion of the workpiece overlying the throat is not supported by the table sections.